Recording Audio

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Cheemag
Posts: 13
Joined: Sun Apr 02, 2017 7:15 pm

Recording Audio

Postby Cheemag » Mon Apr 03, 2017 6:07 pm

I was thinking of buying the SDRplay2, but I'm confused about recording.

I need to be able to record several frequencies without having to listen to any
one of them, often two different frequencies at the same time.

I understand that recording in .WAV isn't possible, but is to come in the future.

There is mention of recording the IQ outputs, but I'm not quite sure how this is
used and whether simultanious recordings can be made.

It would also be useful to be able to have the software bring up a frequency and
record over a specific time period. HDSDR can do this, but it's totally unreliable
as very often it doesn't tune the receiver when doing so.

Would SDRuno meet any of these requirements?

Regards,

Cheemag
Last edited by Cheemag on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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Tech_Support
Posts: 223
Joined: Mon Jun 01, 2015 7:00 pm

Re: Recording Audio

Postby Tech_Support » Tue Apr 04, 2017 5:58 am

Hello Cheemag,
SDRuno records all signals within the bandwidth of the spectrum that is being monitored. So for example, whatever bandwidth you are monitoring (as determined by your sample and decimation rates, but up 10 10 MHz), anything within this segment of spectrum will be recorded. This is what is meant by recording in I/Q format. SDRuno does record in a .WAV format, but the signal scrambled so that it will only play back in SDRuno. We plan a new release in the future that will give the user facility to record signals without scrambling should they so wish.

Sincerely

SDRplay Tech_Support

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Cheemag
Posts: 13
Joined: Sun Apr 02, 2017 7:15 pm

Re: Recording Audio

Postby Cheemag » Tue Apr 04, 2017 12:41 pm

GM OM,

So in order to record two stations I'd have to record the whole 10 MHz over the
time period when the stations were active, then trawl through the recorded IQ
to find what I wanted. Disc space !!

Otherwise I'd be restricted to tuning one station and recording it with Total Recorder,
RecAll Pro or Audacity. I have the a Pro version of a well-known VAC system but I don't
know if that would help with regards to starting and stopping the recording.

I still think I'll buy the SDRplay in hope of achieving a more flexible recording system
later and perhaps HDSDR could be persuaded to work properly with SDRplay as it doesn't
with the CCW SDR4+. I'll ask in another board about HDSDR and SDRplay.

73, Jim
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Tech_Support
Posts: 223
Joined: Mon Jun 01, 2015 7:00 pm

Re: Recording Audio

Postby Tech_Support » Tue Apr 04, 2017 4:53 pm

Hello Jim,
You don't have to record 10 MHz of bandwidth. That is the maximum that you can record at any one time. The minimum is 250 kHz.

We do provide full support for HDSDR via our ExtIO plugin

Best regards

SDRplay Tech_Support

Reason: No reason

hfsdpk11
Posts: 26
Joined: Mon May 01, 2017 5:00 pm

Re: Recording Audio

Postby hfsdpk11 » Sun May 07, 2017 11:57 am

Hopefully, I'm understanding your need as wanting to record the audio of several RF frequencies within the RSP IF bandwidth to a single audio wav, mp3 or similar file. One way to do that is to firstly launch your favourite PC audio recorder (I use Audacity because it's supported by both Windows and Linux) and check that you can direct SDRU audio to it. Multiple frequencies can be recorded by opening as many VRXs as you need, up to the limit of SDRU and your processor capability. The audio output of each VRX is then mixed to whichever channel you want (left, right or both (VRX SETT-OUT) and recorded to the corresponding track by the PC audio recorder. The disadvantage is that you'd need to leave the audio enabled on the PC, i.e. you can't leave it quiet because you're directing speaker audio to the recorder. The only way I can think to mute the PC audio is to insert a headphone plug so as to disable the PC's on-board speakers but then you couldn't listen to another VRX independently.

I haven't tried this, but it may be possible to direct audio from the VRXs you want to hear to a different output device than "speakers" provided you have an alternate device installed on your PC. It may be possible, then, to direct your "quiet" channels to speakers and "active" channel(s) to the alternate WME device, e.g. a bluetooth headset. I say this because audio output direction is done within the VRX environment rather than globally within SDRU (thanks, developers for making that choice).

An enhancement I'd suggest for SDRPlay developers is to make available an audio channel that encodes the time carried by SDRUno as an IRIG-B signal so it could be recorded to an alternate track of a stereo audio recording, e.g. (1) user directs all VRX audio to right channel, (2) user directs IRIG-B to left channel. Of course, to be useful, one would need an IRIG decoder to display the time when playing back the audio file (wink, wink to developers ;-) )
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